private void txt1_TextChanged_1(object sender, EventArgs e)
      {
          
           
          if (txt1.Text == string.Empty)
          {
              return;
          }
          else
          {
              txt1.Text = string.Format("{0:0,00}", double.Parse(txt1.Text));
              txt1.Select(txt1.Text.Length, 0);
          }
      }